Question

Solve this confidence interval problem using a confidence level for that specific classmate’s problem. Make sure that you use appropriate terminology to state the problem and explain your solution.

I asked 20 of these ladies "What age were you when you gave birth to your first child?" I got a range of ages which are: 22, 26, 17, 15, 18, 19, 22, 23, 32, 25, 35, 37, 40, 18, 21, 27, 30, 22, 19, 29. I want the confidence interval to be 95%. Three people indicated they were 22, so I want that to be the random sample.

Please have a description of the data , the confidence level you are using, the z-critical, or t-critical value to be used in the formula, the mean or proportion that represents the data , StDev Margin of Error (MoE) - how it is calculated (formula) and the LL and UL how they were calculated (formula) OR the Stat Crunch (or Excel) Function you used along with the parameters you entered.    ALSO: The statistical statement that gives the interpretation of the results.

Answer 1

Sample size = n = 20

Sample mean = = 24.85

Standard deviation = s = 7.0508

We have to construct 95% confidence interval.

Formula is

Here E is a margin of error.

Degrees of freedom = n - 1 = 20 - 1 = 19

Level of significance = 0.05

tc = 2.093   ( Using t table)

So confidence interval is ( 24.85 - 3.2999 , 24.85 + 3.2999) = > ( 21.5501 , 28.1499)

Interpretation:

We are 95% confidence that the population mean of age is lies in to (21.5501, 28.1499)